Chatting bacteria hike atmospheric CO2

Kate Taylor, 13th October 2011

Bacteria in the ocean are communicating and cooperating in a phenomenon which could be having a significant impact on the planet's climate.

In the water, bacteria coalesce on tiny particles of carbon-rich detritus as they sink down through the depths. And, now, Woods Hole Oceanographic Institution (WHOI) scientists have discovered that these bacteria send out chemical signals to see if other bacteria are in the neighborhood.

If enough others are nearby, the bacteria all commence secreting enzymes that break up the carbon-containing molecules within the particles into more digestible bits.

"We don't often think about bacteria making group decisions, but that is exactly what our data suggest is happening," says WHOI marine biogeochemist Laura Hmelo, now at the University of Washington.

The carbon in the particles derives from atmospheric carbon dioxide, a heat-trapping greenhouse gas. And, says the team, bacterial communication could be leading to the release of carbon from the particles at shallow depths, rather than the ocean's depths.

Thus, the bacterial communication means that less carbon dioxide is drawn out of the air and transferred to the bottom of the ocean, where it can't easily return to the atmosphere.

"So microscopic bacteria buffer the amount of carbon dioxide in the atmosphere through their 'conversations,'" says biogeochemist Benjamin Van Mooy.

"I think it's amazing that there are a near-infinite number of these conversations going on in the ocean right now, and they are affecting Earth's carbon cycle."